The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
An electrically heated diesel particulate filter (DPF) filters particulates or soot from the exhaust stream of a diesel internal combustion engine. When the DPF is full of soot it is regenerated by passing an electrical current through a heating element that is proximate to the DPF. The heater heats a portion the accumulated soot to its combustion temperature. The heated soot ignites, turns to gas, and passes through the DPF, thereby clearing it for another filtering cycle. The soot that is ignited by the heater also begins a flame or ember front that propagates through the remaining soot to also clear it from the DPF during the regeneration cycle.
An electrical system of the vehicle provides power for the heater. Since the exhaust gas carries heat away from the heater and reduces its temperature, the amount of power necessary to ignite the soot is based in part on the exhaust flow rate through the DPF. At high exhaust flow rates the power from the electrical system may be insufficient to heat the heater to a temperature that will ignite the soot during the regeneration cycle.